Monocyte-derived dendritic cells in bipolar disorder.

BACKGROUND: Dendritic cells (DC) are key regulators of the immune system, which is compromised in patients with bipolar disorder. We sought to study monocyte-derived DC in bipolar disorder. METHODS: Monocytes purified from blood collected from DSM-IV bipolar disorder outpatients (n = 53, 12 without lithium treatment) and healthy individuals (n = 34) were differentiated into DC via standard granulocyte-macrophpage colony-stimulating factor/interleukin-4 culture (with/without 1, 5, and 10 mmol/L lithium chloride). The DC were analyzed for DC-specific and functional markers and for T-cell stimulatory potency. RESULTS: Monocytes of bipolar patients showed a mild hampering in their differentiation into fully active DC, showing a weak residual expression of the monocyte marker CD14 and a relatively low potency to stimulate autologous T cells. Lithium treatment abolished this mild defect, and monocyte-derived DC of treated bipolar patients showed signs of activation (i.e., an up-regulated potency to stimulate autologous T cells and a higher expression of the DC-specific marker CD1a). This activated phenotype contrasted with the suppressed phenotype of monocyte-derived DC exposed to lithium in vitro (10 mmol/L) during culture. CONCLUSIONS: Dendritic cells show mild aberrancies in bipolar disorder that are fully restored to even activation after in vivo lithium treatment.

Accessory cells with a veiled morphology and movement pattern generated from monocytes after avoidance of plastic adherence and of NADPH oxidase activation. A comparison with GM-CSF/IL-4-induced monocyte-derived dendritic cells.

Veiled cells (VC) present in afferent lymph transport antigen from the periphery to the draining lymph nodes. Although VC in lymph form a heterogeneous population, some of the cells clearly belong on morphological grounds to the Langerhans cell (LC)/ dendritic cell (DC) series. Here we show that culturing monocytes for 24 hrs while avoiding plastic adherence (polypropylene tubes) and avoiding the activation of NADPH oxidase (blocking agents) results in the generation of a population of veiled accessory cells. The generated VC were actively moving cells like lymph-borne VC in vivo. The monocyte (mo)-derived VC population existed of CD14(dim/-) and CD14(brighT) cells. Of these the CD14(dim/-) VC were as good in stimulating allogeneic T cell proliferation as immature DC (iDC) obtained after one week of adherent culture of monocytes in granulocyte-macrophage-colony stimulating factor (GM-CSF)/interleukin (IL)-4. This underscores the accessory cell function of the mo-derived CD14(dim/-) VC. Although the CD14(dim/-)VC had a modest expression of the DC-specific marker CD83 and were positive for S100, expression of the DC-specific markers CD1a, Langerin, DC-SIGN, and DC-LAMP were absent. This indicates that the here generated CD14(dim/-) VC can not be considered as classical LC/DC. It was also impossible to turn the CD14(dim/-) mo-derived VC population into typical DC by culture for one week in GM-CSF/IL-4 or LPS. In fact the cells died tinder such circumstances, gaining some macrophage characteristics before dying. The IL-12 production from mo-derived CD14(dim/-) VC was lower, whereas the production of IL-10 was higher as compared to iDC. Consequently the T cells that were stimulated by these mo-derived VC produced less IFN-gamma as compared with T cells stimulated by iDC. Our data indicate that it is possible to rapidly generate a population of CD14(dim/-) veiled accessory cells from monocytes. The marker pattern and cytokine production of these VC indicate that this population is not a classical DC population. The cells might earlier be related to the veiled macrophage-like cells also earlier described in afferent lymph.

Distinct monocyte gene-expression profiles in autoimmune diabetes.

OBJECTIVE: There is evidence that monocytes of patients with type 1 diabetes show proinflammatory activation and disturbed migration/adhesion, but the evidence is inconsistent. Our hypothesis is that monocytes are distinctly activated/disturbed in different subforms of autoimmune diabetes. RESEARCH DESIGN AND METHODS: We studied patterns of inflammatory gene expression in monocytes of patients with type 1 diabetes (juvenile onset, n = 30; adult onset, n = 30) and latent autoimmune diabetes of the adult (LADA) (n = 30) (controls subjects, n = 49; type 2 diabetic patients, n = 30) using quantitative PCR. We tested 25 selected genes: 12 genes detected in a prestudy via whole-genome analyses plus an additional 13 genes identified as part of a monocyte inflammatory signature previously reported. RESULTS: We identified two distinct monocyte gene expression clusters in autoimmune diabetes. One cluster (comprising 12 proinflammatory cytokine/compound genes with a putative key gene PDE4B) was detected in 60% of LADA and 28% of adult-onset type 1 diabetic patients but in only 10% of juvenile-onset type 1 diabetic patients. A second cluster (comprising 10 chemotaxis, adhesion, motility, and metabolism genes) was detected in 43% of juvenile-onset type 1 diabetic and 33% of LADA patients but in only 9% of adult-onset type 1 diabetic patients. CONCLUSIONS: Subgroups of type 1 diabetic patients show an abnormal monocyte gene expression with two profiles, supporting a concept of heterogeneity in the pathogenesis of autoimmune diabetes only partly overlapping with the presently known diagnostic categories.

An imbalance in the production of IL-1beta and IL-6 by monocytes of bipolar patients: restoration by lithium treatment.

OBJECTIVES: To study the ex vivo interleukin (IL)-1beta and IL-6 production of monocytes in bipolar disorder (BD) patients in the absence/presence of lithium. METHODS: Monocytes of outpatients with DSM-IV BD (n=80, of whom 64 were lithium-treated) and of healthy control subjects (n=59) were cultured in vitro and exposed (24 h) or not exposed to lipopolysaccharide (LPS) and/or graded concentrations of lithium chloride (LiCl). IL-1beta and IL-6 production was assessed by enzyme-linked immunosorbent assay (ELISA) (supernatants). RESULTS: Monocytes stimulated by LPS from non-lithium-treated bipolar patients were characterized by an abnormal IL-1beta/IL-6 production ratio, i.e., low IL-1beta and high IL-6 production. Lithium treatment increased IL-1beta and decreased IL-6 production and thus restored the aberrant ratio. In vitro exposure of monocytes to LiCl did not have the same effects as lithium treatment: the procedure decreased IL-1beta production and had minimal effects on IL-6 production. CONCLUSIONS: Blood monocytes have an altered proinflammatory status in BD. Lithium treatment restores this altered status. Short-term in vitro exposure of monocytes to lithium has other effects than lithium treatment.

A relative resistance of T cells to dexamethasone in bipolar disorder.

OBJECTIVE: A relative resistance of immune cells to steroids has been established in patients with major depression (MD). In this study, we investigated the in vitro responsiveness of T cells to dexamethasone (DEX) of patients with bipolar disorder (BD). METHODS: T cells of outpatients with DSM-IV BD (n = 54) and of healthy control subjects (HC; n = 29) were isolated, cultured and stimulated with phytohemagglutinin (PHA) for 72 h. The suppressive effect of graded concentrations of DEX (5 x 10(-9)-10(-5) M) on PHA-induced CD25 (IL-2R) expression was measured by fluorescence-activated cell sorting (FACS) analysis. Data were correlated to the T-cell activation status in the peripheral blood of the same patients and to their diagnosis, current mood state, ultradian cycling pattern and current use of medication, including lithium. RESULTS: T cells of patients with BD were less sensitive to DEX-induced suppressive effects as compared with T cells of HC. These data were particularly evident at 10(-7) M DEX (mean % suppression +/- SEM BD: 18.9% +/- 3.5 versus HC: 35.8% +/- 4.7, p = 0.001). We found no correlations of this relative in vitro DEX resistance of T cells neither with the previously mentioned clinical characteristics nor with the actual activation status of the T cells in the BD patients. CONCLUSION: A relative T-cell resistance to steroids, as has been observed in MD previously, may be a trait phenomenon of BD, independent of mood state.

Stretch-induced paracrine hypertrophic stimuli increase TGF-beta1 expression in cardiomyocytes.

Cardiac hypertrophy refers to the abnormal growth of cardiomyocytes, and is often caused by valvular heart disease and hypertension. It involves the activation of growth, including increased protein synthesis and changes in gene expression. Transforming growth factor-beta1 (TGF-beta1) may play a central role in protecting the heart during the hypertrophic response by helping to restore normal functions of the affected myocardium. We tested the hypothesis that cardiomyocytes respond to stretch-induced paracrine hypertrophic stimuli with increased expression of TGF-beta1. To that purpose, we investigated whether angiotensin II (All), endothelin- I (ET-1) and TGF-beta, secreted by stretched cardiac and vascular cells, are involved in the paracrine mechanisms of stretch-induced changes of TGF-beta1 mRNA expression in stationary (i.e. non-stretched) cardiomyocytes. Our results indicated that TGF-beta1 mRNA expression in stationary cardiomyocytes was increased by AII release from cardiomyocytes that had been stretched for 30-60 min. Furthermore, it is likely that ET-1 and TGF-beta were released by stretched cardiac fibroblasts and endothelial cells to induce TGF-beta1 mRNA expression in stationary cardiomyocytes. Stretched vascular smooth muscle cells did not influence TGF-beta1 mRNA expression in stationary cardiomyocytes. These results indicate that AII, ET-I and TGF-beta, released by cardiac cell types, act as paracrine mediators of TGF-beta1 mRNA expression in cardiomyocytes. Therefore, we conclude that in stretched myocardium the cardiomyocytes, cardiac fibroblasts and endothelial cells take part in intercellular interactions contributing to cardiomyocyte hypertrophy.